Process for electrically upsetting rod-shaped metal blanks,and die for carrying out the process



NOV. 4, 1969 M NN 3,476,911

PROCESS FOR ELECTRICALLY UPSETTING ROD-SHAPED METAL BLANKS, AND DIE FORCARRYING OUT THE PROCESS Filed Feb. 9, 1967 5 Sheets-Sheet 1 7 1 I2 .9/guide electrode Fly 3 I I ram ram g l9 I -onvil elecrrode ll. i r;:# "7"7- Fi I A A} l 1 l H t i J 10 i "I T lnven/ar:

HORST BACHMANN ATTORNEYS Nov. 4, 1969 Filed Feb. 9, '1967 H. BACHMANN3,476,911

PROCESS FOR ELECTRICALLY UPSETTING ROD-SHAPED METAL BLANKS, AND DIE FORCARRYING OUT THE PROCESS s Sheets-Sheet z In venfar HORST BACHMANN ATTORNE Y5 NOV. 4, 1969 BACHMANN 3,476,911

PROCESS FOR-ELECTRICALLY UPSETTING ROD-SHAPED METAL BLANKS, AND DIE FORCARRYINGIOUT THE PROCESS Filed Feb 9, 196'? I 3 Sheets-Sheet 5 In van/orHORST BACHMANN M, ma

A T TORNEYS United States Patent 8 48 Int. Cl. Hb I/OO; B21d 37/16; G01k1/14 U.S. Cl. 219-151 14 Claims ABSTRACT OF THE DISCLOSURE Electricallyupsetting generally rod-shaped metal blanks in a die is done by a ramexerting the upsetting force, and a block carrying an anvil electrodeand movable in the die in the direction of the upsetting force, toproduce the counter-thrust required for upsetting. The die is movable inan outer sleeve. Initially, the die is held stationary within the sleevewhile performing a predetermined partial stroke of the block in thedirection of upset. Then the outer sleeve is moved co-directionally withthe continuing movement of the block, as by mechanically locking the dieto the block, after the latter has completed its predetermined partialstroke. The mechanical connection may include an abutment on the blockand a counterstop aligned with the abutment for releasing the lockingmeans.

The invention relates to a process for electrically upsetting generallyrod-shaped metal blanks in a die by means of a ram exerting theupsetting pressure, and a block movable in the die in the direction ofupset producing the counter-thrust required for upsetting.

Electrical upsetting makes it possible to produce trueto-size workpiecesand is often superior to forging in the die because, in contrast to thelatter method, there is no significant scaling or burning-up whichprevent accurate measurements of the raw volume, particularly ifintermediate heating is employed. Also, due to the abrasive efiect ofthese waste materials, forging tools are subject to rapid wear.

In electrical upsetting, the blanks are heated by electrical currentflowing through them and upset in the same operation, mostly by means ofhydraulic power. The method is suitable for rods of round, oval,prismatic or plane cross section. It is a particular advantage of theelectrical upsetting method that any desired lengths of blank can beupset in a single uninterrupted operation. Even if the upset workpiecemust be finally stamped in the die, the electrical upsetting methodoffers the advantage that the workpiece need not be reheated, and finalstamping is carried out in the same heat.

As a result of the particular type of electrical resistance heating fromwithin and the resulting high speed of heating, the workpiece remainssubstantially free of scale. Once proper adjustment has been made,eXcess heating or underheating is avoided. This eliminates burn-up orwaste due to excessive or inappropriate heating. Thus, it becomespossible to so accurately limit the volume of upset that, after finalstamping, workpieces are obtained which are extraordinarily true to sizeand require little or no additional machining. During the electricalupsetting, the rod-shaped blank is held by the clamping jaws of a guideelectrode and firmly urged by the upsetting force acting on the freetrailing end of the rod against an anvil electrode which in most casesis provided with a wearing plate. When the heating current is turned on,it heats the portion of the workpiece located between the Patented Nov.4, 1969 tWo electrodes to forging temperature, and the workpiece isdeformed by the force acting on the trailing end of the blank.

To produce workpieces with any desired length of upset; the anvilelectrode is restracted into the die when the upsetting operation isperformed in the die, or in the case of "free upsetting, the anvilelectrode with its plate are retracted, thus affording more space forthe upset head to thicken without reaching the buckling limit of theheated rod.

With conventional upsetting methods, workpieces can only be producedwhose upset portion has the same diameter over its entire length. It isan object of the present invention to provide in simple manner adeformation method which permits the manufacture of a workpiece whoseupset portion comprises segments of different diameters. In accordancewith the invention, this problem is solved in that a die-sleeve movingin an outer die is at first held stationary with the die and, after theblock has performed a predetermined partial stroke in the direction ofupset, the sleeve is moved in the same direction as the" continuingmovement of the block. After the block has, completed the predeterminedpartial stroke, the diesleeve is preferably automatically connectedthereto. Since during the movement of the die-sleeve a segment of theouter die is exposed, a thicker segment of upset workpiece is formedcorresponding to the larger inner diameter of the outer die. The outerdie, which at first is covered, thus actually becomes effective as a dieover its exposed part. A plurality of sleevelike dies may be mountedinside one another and released successively for movement with theblock, if it is desired to produce a workpiece with multiple offsets.

The invention further relates to a die for carrying out the process. Inaccordance with the invention, the die is constructed so that at leastone inner sleeve is disposed therein, the sleeve moving in the samedirection as the block, after a latch locking it against the stationaryoutside die has been released. With such a die, the leading end of theworkpiece in direction of upsetting is at first upset to a diametercorresponding to that of the inner sleeve. However, as soon as the lockof the inner sleeve which is movable in the direction of upset has beenreleased and the sleeve can retreat together with the block, a largerfree cross section obtains at the input end of the die and is filledwith the oncoming upset material. The finished workpiece thus comprisesa part of smaller diameter which has been upset first, and a connectingpart of larger diameter, the length of the two parts depending on thelength of upset obtaining when the locking of the inner sleeve isreleased.

The locking can be released at the appropriate moment automatically andsimply by providing the block with an abutment which, after traversing apredetermined path, runs against and pushes out a counter-stop torelease the lock. The counter-stop may project through a slot in theinner sleeve into the path of movement of the abutment connected to theblock.

A cam secured to a rocking lever may also be used to serve as thecounter-abutment, the rocking lever compris ing a locking notch abuttingagainst a supporting surface of the inner sleeve. By suitablyconstructing the rocking lever, the speed ratio between the deflectionof the counter-stop and the movement of the locking notch intounlatching position can be influenced so that unlatching occurspromptly, whereby greater accuracy of the length of the workpiece headis achieved.

In order to eliminate the necessity of the workpiece transmitting thepower for moving the inner sleeve codirectionally with the block via thefront wall of the sleeve, a contact surface is preferably provided inback of the counter-stop, seen in the direction of stroke, which isfixedly connected with the inner sleeve and onto which the abutment runsafter deflection of the counter-stop. The block thereby automaticallyentrains the sleeve in the same direction, and undesired bulgelikeobstructions of the material in the heating zone in front of the dieinlet is avoided. If a head of small diameter is to be upset, followedby a segment of larger diameter, upsetting of the thinner head, becauseof the lesser upsetting ratio, requires a greater speed of deflection ofthe counter-stop than is the case when upsetting the thicker segment.Different workpiece segments must be upset with a variable pressureand/or heating current. A simple device for adjusting these operationalvalues comprises a control member actuated by the counter-stop andcontrolling the speed of deviation, the upsetting pressure, and theheating current. In general, an electrical limit switch is used whichtriggers the required impulses.

In a logical application of the inventive concept, if workpieces arebeing produced which comprise a plurality of segments of diametersincreasing in the direction of upset, more than one longitudinallymovable inner sleeve may be provided. The sleeves, fitting into oneanother, are at first secured in their starting position againstlongitudinal movement and, when the segment which is in the process ofbeing upset has reached the desired length, they are releasedsuccessively for movement co-directionally with the block.

The invention is described hereinbelow in greater detail in connectionwith the drawings.

In the drawings:

FIG. 1 is a view in longitudinal section through a die embodying theprinciples of the invention.

FIG. 2 is a fragmentary view in section taken along the line 11-11 ofFIG. 1.

FIG. 3 is a sectional diagram of the die of FIG. 1, during upsetting ofthe first segment of the workpiece...

FIG. 4 is a similar view of the device of FIG. 3 during upsetting of asecond workpiece segment of larger diameter.

FIG. 5 is a view in longitudinal section of a modified embodiment of theinvention.

FIG. 6 is a view in cross section of the device of FIG. 5 taken alongthe line VIVI in FIG. 5.

In FIG. 1, a die holder 1 is suitably mounted on the frame of aconventional electrical upsetting machine, not shown. A die 2 is securedin the holder 1 by means of a holding plate 3, the die 2 beingexchangeable, as necessary, after release of screws 4. The holding plate3 preferably has a tubular extension 5.

An inner sleeve 6, also acting as a die, is disposed in the die 2, andits leading end (reading in the direction of upset) is connected with anextension 7, as by means of a screw coupling 8. The entire inner sleeve6 is thus exchangeable. At its input end, the sleeve 6 is provided witha wearing member 6a. Since wear is heaviest at the inlet end of thesleeve *6 which acts as a die, the wearing member 6a is alsoexchangeable, for example, by means of a screw connection. The sleeve 6and the extension 7 are axially movable in the die 2 and its extension5.

A block 9 equipped with a wearing plate 9a at its end facing the openingof the die moves in the interior of the sleeve 6. The block 9 and thewearing plate 9a form an anvil electrode.

At its end opposite the die opening, the block 9 is equipped with apiston 10 which is guided in a pressuremedium cylinder (not shown).Usually, the constant pressure of the pressure medium urges the piston10 in the direction of the upsetting stroke, while the requiredcounter-pressure is generated in the opposite cylinder chamber by anadjustable constant-pressure valve. The block 9 may thus be moved fromthe starting position shown in FIG. 1 to the left against a forcegenerating the counterpressure needed for upsetting and, aftertermination of the upsetting process, the block 9 may be returned intoits starting position, for example, by reversing the pressure-mediumcylinder.

.4 An abutment 11 is secured to the block 9 and projects radially pastthe periphery of the block 9. The abutment 11 engages in an elongatedslot 12 in the extension 7 of the sleeve 6. At the forward end of theelongated slot 12, seen in the direction of upset, a transverse slot 13is provided in the extension 7, the slot 12 terminating in the slot 13.A latching cam 14, projects into the slot 13, its end disposed insidethe slot having an inclined surface 15 onto which the abutment 11 runsas soon as the block 9 has moved to the left, during upsetting, by alength corresponding to that of the slot 12. As soon as the abutment 11has forced the latching cam 14 outwardly against the action of a spring16 which urges it inwardly, the cam 14 comes out of engagement with theholding surfaces formed laterally of the point of transition of theelongated slot 12 into the transverse slot 13. This releases the sleeve6 from the position shown in FIG. 1, and it can also move to the leftunder the influence of the pressure transmitted by the workpiece. Alarger cross-sectional area is thereby exposed at the input end of thedie and is thereupon filled with the material of the workpiece.

The arrangement of the lock illustrated in the embodiment of FIG. 1 isshown in FIG. 2 on an enlarged scale and in partial cross section. Itwill be seen that the cam 14, which is movable radially of the die, isguided in a housing 17 connected with the extension 5 and closed by acover 18. FIG. 2 also shows the holding surfaces with which the cam 14secures the sleeve 6 against longitudinal displacement, so long as thelock has not been cleared. The latching surfaces are located between thelateral boundaries of the elongated slot 12 and the circumferential endsof the transverse slot 13.

The operation of the die in accordance with the invention is illustratedschematically in FIGS. 3 and 4. A rodshaped blank 19 is introduced intothe die through the clamping jaws of a guide electrode 21 by means of aram 20 which may be, for example, hydraulically actuated. The leadingend of the blank 19 abuts on the anvil electrode or block 9 so that,when the current is turned on, it heats the part of the blank 19 betweenthe forward end of the block 9 and the guide electrode 21. As the blank19 is advanced by means of the ram 20 while the block 9 retreats, thoughat a lesser speed, a thickened upset portion 19a is formed.

As soon as the part 19a of the blank 19 has reached the desired lengthand the abutment 11 on the block 9 has cleared the lock 14 holding thesleeve 6, the sleeve 6 begins to move co-directionally with the block 9.The cross-sectional area at the input end of the die is thereby enlargedso that, as upsetting of the blank proceeds, a segment 19b (FIG. 4) isformed which has a larger diameter than the part 19a. The upsettingprocess is terminated when the part 19b has also attained the desiredlength. Since the part of the blank 19 located between the guideelectrode 21 and the ram 20 is not heated, any desired lengths ofrod-shaped blank 19 may be processed.

FIGS. 5 and 6 illustrate a modified embodiment of the arrangement of thedie holder in the machine frame 22 in further detail. To avoid excessiveheating and thereby premature wear of the die, the part most affected bythe heat is cooled. Hollow spaces are provided for this purpose in theinterior of a sheath surrounding the die holder 1A, for passing coolingfluid therethrough. The die holder 1A is equipped with cooling ribs at1a. The cooling medium is supplied and discharged through pipeconnections 1b and 1c.

The axially displaceable block 9 is provided with an exchangeable anvilelectrode 9a at its end facing the workpiece.

As in the previously described embodiment, the twopart die comprises anouter sleeve-like member 2 and an inner sleeve 6. The inner sleeve 6 issecured as by threading 8 to a tubular extension 7. The sleeve 6together with the extension 7 is secured in starting position againstlongitudinal displacement by a lock in the form of an angled rockinglever or toggle 23. As shown in FIG. 6, the toggle lever 23 is in theform of a transverse U, so that the part equipped with a locking notch25 (FIG. 5) and directed against the direction of upset, engages in theelongated slot 12 in the extension 7 and abuts against a holding surface7b formed at :the leading end of the slot 12.

The lever 23 is equipped in back of the locking notch 25, seen indirection of the working stroke, with a control cam 26 which alsoengages in the elongated slot 12. A double-cone thickening 11a on theblock 9 forms an abutment which, after having completed a predeterminedstroke, runs up the control cam 26 and presses the toggle lever 23upwardly. The toggle lever 23 rotates about a pivot pin 24 disposedbetween supporting brackets 24a on the machine frame 22. As the abutment11a swivels the toggle lever 23, the notch 25 comes out of contact withthe holding surface 7b, so that the sleeve 6 participates in thelongitudinal movement of the block 9. The sleeve 6 is automaticallyentrained at the same speed because, after dislocating the toggle lever23, the abutment 11a abuts against a bearing surface 70. The bearingsurface 7a is formed by a collet 70 at the trailing end of the tubularextension 7 and serves simultaneously for guiding the block 9 during thefirst part of the upsetting process.

An actuating pin 27 abuts against the upper side of the top arm of thetoggle lever 23 and moves longitudinally in a screw plug 38,transversely to the direction of stroke of the block 9. Between thescrew plug 38 and a head 27a at the lower end of the actuating pin 27, aspring 37 is provided which maintains the pin 27 in constant abutmentagainst the toggle lever 23 and also takes care that the toggle lever 23should properly engage in the elongated slot 12 when the die is in itsstarting position.

The upper end of the actuating pin 27 is provided with a conical point29 which acts on an actuating member 30 when the pin is moved upwardlyas the lever 23 is dislocated. The member 30 belongs to a limit switch28 which, as shown in the drawing, is actuated when the abutment 11aswivels the toggle lever 23 from its starting position into releasingposition and thereby releases the sleeve 6 for axial movement.

The limit switch 28 changes the speed of deviation of the block 9, forexample, by displacing a pressure-medium cylinder actuating aconstant-pressure valve on the block 9. Since during the first part ofthe upsetting process, the workpiece is upset to a smaller diameter thanin the second part thereof, the block 9 must, because of the lesserupsetting ratio, have a greater speed of deviation (i.e., speed relativeto the speed of the workpiece) during the first part of the process thanduring the second part thereof, because the larger diameter upset duringthe second part requires the feed of a larger amount of material perunit of time.

If desired, the limit switch 28 may also vary the heating current comingfrom the electrodes and/ or the upsetting pressure exerted by the ram20. Increased heating current supply and/or pressure during upsetting ofthe workpiece segment of larger diameter may be necessary in order tocarry out the process without lags even when working is done at agreater upsetting ratio.

Since the spring-loaded actuating pin 27 seeks to maintain the togglelever 23 in engagement with the elongated slot 12, yet the toggle lever23 must be swiveled into releasing position when the die is to beremoved from its hold, for example after loosening the screws 4 inaccordance with FIG. 5 in the direction toward the viewer, a device isprovided which lifts the pin 27 against the action of the spring 37 andmaintains it in raised position. The device comprises a manual lever 32disposed in a bearisg 34 and swiveling about a horizontal axis. The endof the lever 32 facing the pin 27 is bifurcated, and in these forkedends, oblong holes 33 are provided which are substantially parallel withthe pin 27. A transverse pin 31 secured to the pin 27 engages in saidoblong holes 33. The oblong hole 33 is so shaped that, in the positionof the lever 32 shown in FIG. 5, the pin 27 may move up and down foractuating the terminal switch 28. When the end of the lever 32 facingaway from the pin 27 is depressed, it lifts the pin 27. To secure thelever 32 in this position, a latching device is provided. In theillustrated embodiment, it comprises a resiliently swiveling hook 36which, when the right end of thgeslever 32 is depressed, is lowered overa projecting pin FIG. 5 shows the laterally twice-angled or steppedshape of the toggle lever 23. The locking notch 25 and the control cam26 are mounted at the upper, horizontally extending arm of the lever 23,both standing above the elongated slot 12, or engaging therein duringthe first part of the upsetting process. Below the die, the pivot pin 24is mounted between the support brackets 24a, the lever 23 swivelingabout them when the abutment 11a impinges on the control cam 26.

The advantage of the releasable lock shown in FIGS. 5 and 6 as comparedwith the embodiment of FIGS. 1 and 2 is that no frictional resistanceneed be overcome when the toggle lever is swiveled, as is the case whendisplacing the locking cam 14 in accordance with FIGS. 1 and 2.

To those skilled in the art to which this invention relates, manychanges in construction and widely difiering embodiments andapplications of the inventions will suggest themselves without departingfrom the spirit and scope of the invention. The disclosures and thedescription herein are purely illustrative and are not intended to be inany sense limiting.

I claim:

1. In an apparatus for upsetting metal rods and the like in a die bymeans of a ram exerting the upsetting force and anvil means movable inthe die in the direction of the upsetting force and providing thecounter-thrust required for upsetting the improvement comprising atleast one inner sleeve disposed in said die and movable codirectionallywith said anvil means, and holding means for locking said sleeve againstsaid die during at least some portion of the movement of said anvilmeans.

2. The apparatus of claim 1 wherein said anvil means has an abutment,means defining a predetermined path for said abutment, and counter-stopmeans aligned with said abutment for releasing said holding means.

3. The apparatus of claim 2 wherein said inner sleeve has a slot, saidcounter-stop means projecting through said slot into the path ofmovement of said abutment.

4. The apparatus of claim 3 wherein said sleeve has a first elongatedslot and a second slot following said first elongated slot when movingin the direction of upset, said abutment engaging in said first slot, alocking member in said second slot having a holding surface located atthe transition of the elongated slot into said second slot, said holdingsurface being effective between said inner sleeve and said holdingmember.

5. The apparatus of claim 4 wherein said holding member comprises aspring and a cam displaceable transversely to the direction of movementof said inner sleeve against the action of said spring, said cam havingan inclined surface rising against the direction of movement of saidanvil means and projecting into the path of movement of said abutment.

6. The apparatus of claim 3 including a rocking lever, said counter-stopcomprising a cam secured to said rocking lever, said rocking leverhaving a locking notch abutting against a holding surface of said innersleeve.

7. The apparatus of claim 6 including a bearing surface in back of saidcounter-stop and fixedly connected to said sleeve, said abutmentengaging said bearing surface after said counter-stop has beendeflected.

8. The apparatus of claim 7, including a switch member actuated by saidcounter-stop for controlling any of the speed of deflection of saidanvil means, the upsetting pressure, and the heating current.

9. In an apparatus for electrically upsetting generally rod-shaped metalblanks in a stationary outside die by means of a ram exerting theupsetting force and a block movable in the die in the direction of theupsetting force which produces the counter-thrust required for upsettingand means for electrically heating the blank being upset, theimprovement comprising: at least one inner sleeve disposed in said dieand movable co-directionally with said block, and means for locking saidsleeve against said stationary outside die during at least some movementof said block.

10. The apparatus as described in claim 9 including an abutment on saidblock; means forming a predetermined path for said abutment; and acounter-stop aligned with said abutment for releasing the locking means,said counter-stop projecting through a slot in said inner sleeve intothe path of movement of said abutment.

11. A method for upsetting metal rods and the like in a die by means ofa ram exerting the upsetting force, and a block movable in the die inthe direction of the upsetting force to produce the counter-thrustrequired for upsetting said die moving in an outer sleeve, comprisingthe steps of:

initially holding the die stationary within said sleeve while performinga predetermined partial stroke of the block in the direction of upset,and

then moving said outer sleeve co-directionally with the continuingmovement of the block.

12. The method of claim 11 including the step of mechanically connectingthe die to the block after the latter has completed the predeterminedpartial stroke.

13. A method for electrically upsetting generally rodshaped metal blanksin a die by means of a ram exerting the upsetting force, and a blockmovable in the die in the direction of the upsetting force whichproduces the counter-thrust required for upsetting, comprising the Stepsof:

providing an outer sleeve within which said die can move;

electrically heating the end of each metal blank;

initially holding the die stationary within said sleeve While performinga predetermined partial stroke of the block in the direction of upset,and

moving said outer sleeve co-directionally With the continuing movementof the block.

14. The method as described in claim 13 including the step ofmechanically connecting the die to the block after the latter hascompleted the predetermined partial stroke.

References Cited UNITED STATES PATENTS 2,581,774 l/1952 Stone et al.219-151 2,621,344 12/1952 Friedman 72-354 X 3,283,556 11/1966 Putetti eta1. 72354 X 3,347,081 10/1967 Bachmann 72-342 FOREIGN PATENTS 475,5734/1929' Germany. 863,588 1/1953 Germany. 26,150 11/1963 Germany.

JOSEPH V. TRUHE, Primary Examiner B. A. STEIN, Assistant Examiner US.Cl. X.R.

